Plaquemine Lock is that dangerous love affair you warn your best friend to avoid. Leave it, mate. They’re not worth it. It will only end in heartbreak and, this being a lousy metaphor for restaurant failure, debt. But Jacob Kenedy will not be told. The chef renowned for his gutsy Italian cooking at Soho’s Bocca di Lupo has chosen to take over a north London pub and turn it into a celebration of the food of the Louisiana basin. Because on a hot summer’s day, with the smell of diesel rising off the foetid waters of the nearby Regent’s Canal, Islington is exactly like New Orleans. Kinda.

Crayfish are offered by the pound, with potatoes and corn on the cob. They are boiled and spiced and impressive

The food of Louisiana needs some unpacking. The locals will tell you it is the United States’ one original culinary tradition, partly because the lexicon is full of fancy French words like etouffée, boudin and andouille, courtesy of the first Francophone colonials. The andouille of Louisiana is nothing like the sweaty bum-crack andouillette from the mother country – it’s just a smoked spiced sausage – but the root is similar.

Which is to say the food of New Orleans is about making the best of poverty: there are rugged, gnarly sausages made with belly and loin and eyelid, because none of the pig must be wasted. There are stews in flour-thickened sauces, because it’s the cheapest way to make humble ingredients go far. There is an intense culture involving fearsome bugs dredged from the waters. Crayfish may look real pretty in their crimson shells, but bugs they remain.

Generally this food doesn’t travel well. Few cooks can resist smoothing off the rough edges. They try to pretty it up; make it fancy-restaurant-friendly. Kenedy has resisted the temptation. In a heated glass cabinet on the bar are greaseproof paper bags full of chunky lumps of pork belly, crisped from the crackled skin to the shattering meaty bits below. They are a declaration of intent. They are announcing that the food here is filthy, but in a really good way.

‘Real pretty in their crimson shells’: crayfish. Photograph: Sophia Evans for the Observer

Then again, Kenedy has skin in the game. The Plaquemine Lock (formally the Prince of Wales pub) is both a love letter to this food and a tribute to his grandmother, Virginia Campbell, who was born into a famous Louisiana family in the town of Plaquemine near Baton Rouge, and who died last year aged 102. She was a Broadway actress who made it to Hollywood, where she worked with Ernst Lubitsch and Cecil B DeMille. She eventually married the writer John Becker, with whom she moved to Rome. They rented a grand apartment bedecked with murals by Poussin, set up a marionette theatre and threw lavish parties attended by the likes of Robert Graves, WH Auden and Federico Fellini. When Fellini came to make La Dolce Vita, he based two key characters on Kenedy’s grandparents. When that marriage ended, she took her puppets on cruise ships where she developed a sideline as a trained plumber. Virginia Campbell sounds like the perfect answer to the dream dinner guest question.

‘Filthy, in a good way’: pork crackling. Photograph: Sophia Evans for the Observer

The walls are painted a hot, sultry yellow overlaid by naive murals of life on the bayou; of plantation houses and river boats. It’s all bare caff tables, cutlery in tins and orders taken at the bar. There are sections for oysters, both raw and grilled, and for Po’boys, overfilled sandwiches stuffed with the likes of “beef debris”. Gumbo, by the cup and bowl, is as it should be: a deep, luscious stew of sausage and chicken, with crawfish added late on so they don’t tense up, in a reassuringly thickened liquor so profound it can give focus to an aimless life.

Over at Bocca di Lupo Kenedy became renowned for his sausage making, and the smoked pork boudin here, served with the nose twitch of pickled okra, is another fine example. This is coarse ground and deep flavoured, a celebration of ripe piginess in all its majesty. The most ambitious dish is the shrimp ’n’ grits. The shrimps are meaty blighters, seared in butter to a reassuring rust, on a porridge of barely ground corn, with fried bacon and ladlefuls of gravy. A bowl of this will stay with you for the day, and probably the day after that, too.

Crayfish – crawfish in the language of this menu – are offered by the pound, with potatoes and corn on the cob. They are boiled and spiced and impressive, curled away like this, in their shells. Eating these is proper work; if you’re worried about breaking a nail, don’t even start. Otherwise, surrender yourself to the process of shell crack and suck and pick. They’re a proper size and reward the effort.

Southern fried chicken is all breast, which risks being dry and dense but isn’t. It comes with a vibrant slaw of the sort deep-fried food demands, and the revelation of pickled watermelon. A side salad with fresh corn kernels, dressed like it’s trying to make an impression at a job interview, also helps. Only collard greens, which should be deep, intense and brassic, miss the mark. These are light and stewed and, at £6, overpriced. Some will find pricing an issue generally: the shrimp and grits and the crayfish are £12, the fried chicken is £10. It mounts up for poor people’s food. Then again this is poor people’s food served up in bourgeois Islington, where everything costs.

Helpfully they serve an extremely good Bloody Mary, properly spiced and properly chilled and not so thick as to demand a hydraulic pump to get it up the straw. Suck it up. It will do you good. There is, as there should be, a pecan pie with a crisp base, alongside a scoop of cane sugar ice cream which manages not to be too sweet. A multilayered rum-soaked sponge Doberge cake of raspberry and chocolate is crying out for a dollop of chilled bourbon Chantilly. These are details.

Jacob Kenedy has had a rough time of late. He had to admit defeat with Vico, his central London trattoria. It was, he has said, too big a space for him. Plaquemine Lock, though seemingly some way from the Italian restaurants for which he is known, is actually on the same territory: by attending to the details it celebrates the virtues of the rough-hewn and the hardcore. It’s not effete and it’s not prissy and it’s all the better for it. You know what: this dangerous love affair may just work out after all.

Jay’s news bites

■ The Tavern, one of Cheltenham’s older pubs, was at one point knocking out a mixture of hearty Mediterranean dishes, alongside Americana. It now appears to have focused on the latter. It does burgers, wings in sauces and a Caesar salad with or without the anchovy. Though without the anchovy I’m not sure it qualifies as a Caesar. No matter; pricing is keen (theluckyonion.com).

■ Fed up of people photographing their dinner rather than eating it? I’m afraid it’s unlikely to get any better. American comfort food outlet Dirty Bones has launched an ‘Instagram foodie pack’ to help you take better images for the socials. It contains an LED camera light, a charger, a clip-on wide-angle camera lens and a selfie stick on a tripod to facilitate overhead table shots. I hate the 21st century.

■ The shabby-chic Pig Hotelgroup, launched by Hotel and Bistro du Vin co-founder Robin Hutson, has seen revenues leap by 42% to £14.2m. This is partly due to new openings but mostly due to an occupancy rate of over 90%.